Legacy Images Not Displaying and odd Redirects

I’ve been troubleshooting some odd behavior on a couple of our multisite installs for some time now, and have been searching these forums but can’t seem to find a fix. Thanks in advance for any feedback!

At some point during recent WordPress updates, certain images are no longer displaying on our main site at http://tripawds.com and our dev install at http://tripawds.net

1. Images exist but don’t display
For years I have used a folder to host some image files I have hard-coded into various templates for different reasons.

I have confirmed the images exist at /blogs.dir/1/files/adpix/ but they do not display in posts or pages and throw a 404 if called directly.

2. Old Media Library Photos Do Not Show
Many older photos in our WP Media Library do not display anymore. Here is an example file location:
http://www.tripawds.com/wp-content/blogs.dir/1/files/friends_family/20080518w_eurekaphoto02.jpg

You will notice this results in Page Not Found, but I have confirmed the file does exist at that URL.

3. Certain Admin Pages Throw 404
I’m not sure if this is related or not, but on our dev install I am not able to access themes.php on certain sites.

Now… I did find support topics suggesting this may likely be caused by our httpd.conf setup, so I have confirmed that AllowOverride is set to all:

<Directory "/">
    Options ExecCGI FollowSymLinks Includes IncludesNOEXEC Indexes SymLinksIfOwnerMatch
    AllowOverride All
</Directory>

I also thought something may be awry with our .htaccess file, so I’m including that for review too:

RewriteEngine On
RewriteBase /

# uploaded files
RewriteRule ^(.*/)?files/$ index.php [L]
RewriteCond %{REQUEST_URI} !.*wp-content/plugins.*
RewriteRule ^(.*/)?files/(.*) wp-includes/ms-files.php?file=$2 [L]
RewriteRule ^(.*/)?sitemap.xml wp-content/sitemap.php [L]
RewriteRule ^(.*/)?global-posts-feed/(.*) wp-content/recent-global-posts-feed.php [L]
RewriteRule ^(.*/)?global-comments-feed/(.*) wp-content/recent-global-comments-feed.php [R=301,L]

# add a trailing slash to /wp-admin
RewriteCond %{REQUEST_URI} ^.*/wp-admin$
RewriteRule ^(.+)$ $1/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule . - [L]
RewriteRule  ^([_0-9a-zA-Z-]+/)?(wp-.*) $2 [L]
RewriteRule  ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

Thanks again for any suggestions.